Preparation And Electrocatalytic Performance Of Transition Metal Nanomaterials Self-supported Electrode

Oxygen electrocatalysis generally involves oxygen reduction reaction(ORR)and oxygen precipitation reaction(OER)and is a key step in energy conversion and storage technologies such as metal-air batteries and hydroelectric cells.Among them,rechargeable metal zinc-air battery has high energy density,low development cost,safe operation and environment friendly.However,the development and use of highly efficient,low-cost and abundant catalytic materials to replace precious metal-based electrocatalysts is still a problem and challenge that has not been completely solved at this stage.Recently,metal-organic frameworks(MOFs)and carbon-based derivatives of MOFs,as highly efficient electrocatalysts,have gradually attracted extensive attention and research interest due to their extraordinary morphology,structure,composition and functional adjustable ability.Therefore,we report a nickel-foamed-supported two-dimensional metal-organic framework and its derivatives coupled array as binderless ORR/OER double-effect catalysts capable of achieving high specific surface area,high conductivity and high bifunctionality,while avoiding the complex preparation process of using organic binders and the inevitable impact on battery performance.Different from the traditional design,this paper mainly integrates different functional components and fully exposes the electrochemical active area to improve the overall activity of the double-effect electrode.Due to its stable multi-stage two-dimensional nanosheet structure during the growth-pyrolysmy-regrow process,the prepared double-effect oxygen electrode material exhibits significantly enhanced bifunctional groups,electrochemical active area,reaction kinetics and stability,and can be further used for rechargeable zinc air batteries(ZABS).Considering the feasibility and simplicity of the preparation process,the growth-pyrolyse-regrowth strategy proposed can not only be used for the synthesis of the coupled hierarchical nanosheet array structure,but also provide reference for the design and development of highly active electrode structures for energy electrochemistry devices.The explorations of low-cost,high-efficient,robust and bifunctional electrocatalysts for both oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)in the electrochemical water splitting(EWS)is urgently desired for further developing renewable-energy storage and conversion techniques.We report a facile and effective one-step molten salt synthesis route to prepare self-supported 1D Ni-Mo based mixed-phase polyionic compounds nanorod arrays(NMNAs),which consist of dominant ammonium nickel molybdenum oxide hydroxide((NH4)Ni2Mo2O8(OH))and secondary nickel nitrate hydroxide(Ni2(NO3)2(OH)2).The as-fabricated NMNAs electrodes deliver a remarkable overall electrocatalytic water splitting performance,with lower overpotential values of 189.9 and 191.2 mV to drive a high current density at 100 mA cm-2 for OER and HER respectively.The enhancement effect due to the introduction of molybdenum in comparison with controlled electrodes has been also confirmed by the increased electrochemical surface area(ECSA).